Question

Решите пж
8x(x+5)-2x(6x+10)=5

Answer 1

$8x(x + 5) - 2x(6x + 10) = 5 \\ 8 {x}^{2} + 40x - 12 {x}^{2} - 20x = 5 \\ - 4 {x}^{2} + 20x = 5 \\ - 4 {x}^{2} + 20x - 5 = 0 | \: \: \: \: \times ( - 1) \\ 4 {x}^{2} - 20x + 5 = 0 \\ d = ( - 20)^{2} - 4 \times 4 \times 5 = 320 \\ \\ x1 = \frac{20 + \sqrt{320} }{2 \times 4} \\ \\ x2 = \frac{20 - \sqrt{320} }{2 \times 4} \\ \\ x1 = \frac{5 + 2 \sqrt{5} }{2} \\ \\ x2 = \frac{5 - 2 \sqrt{5} }{2}$
Готово.